New form for this one, inspired by discussions of the Doppler effect in the physics class I'm auditing. I just love cyclical and repetitive structures in poems generally. Like emotional palindromes, they require both the writer and the reader to retread the same experiences from two different perspectives.

One of my favorite forms, the pantoum, has a structure in which not merely rhyme-sounds, but entire lines are repeated from one stanza into the next: abcd / bedf / egfh / gahc. That's in 4 stanzas, the shortest possible version of the pantoum--they can go on as long as you like. 

I decided to make an even more drastic repetitive requirement for this doppler poem. This first one is a 20-line version, but you can do it for any even number. The first 10 lines, or the "blueshift" half of the poem, describes the subject from one perspective, going from beginning to end. The next 10 lines, or the "redshift" half, goes from end to beginning, interweaving with the first half, and repeats the very same lines with slight changes in phrasing to show the same material from a different perspective. Rhymes are totally optional--and a big challenge to incorporate! Here I've used "I" and "you" for the two perspectives, using the image of two asteroids colliding.

we touched each other once - but why?
your bound inertia shapes the dark
it traces out a silent arc
you gave me something like a name
a flame ellipsis cross the sky
broke your established orbit free
I knocked your vector off its skew
your meteoric speed's the same
however much I miss you by
you are the one who misses me
I am the one who misses you
however much you miss me by
my meteoric speed's the same
you knocked my vector off its skew
broke my established orbit free
a flame ellipsis cross the sky
I gave you something like a name
it traces out a silent arc
my bound inertia shapes the dark
we touched each other once - but why?